Substrate preparations in epitaxial ZnO film growth

Epitaxial ZnO films were grown on two polar surfaces (O-surface and Zn-surf ace) of (0 0 0 1) ZnO single crystal substrates using off-axis magnetron sp uttering deposition. As a comparison, films were also deposited on (0 0 0 1 ) Al2O3 substrates. It was found that the two polar ZnO surfaces have diffe rent photoluminescence (PL) spectrum, surface structure and morphology, whi ch strongly influence the epitaxial film growth. The morphology and structu re of homoepitaxial films grown on the ZnO substrates were different from h eteroepitaxial films grown on the Al2O3 An interesting result shows that hi gh temperature annealing of ZnO single crystals will improve the surface st ructure on the O-surface rather than the Zn-surface. The measurements of PL , low-angle incident X-ray diffraction, and atomic force microscopy of ZnO films indicate that the O-terminated surface is better for ZnO epitaxial fi lm growth. (C) 2001 Published by Elsevier Science B.V.